/* ----------------------------------------------------------------------
 * Project:      CMSIS DSP Library
 * Title:        arm_shift_q15.c
 * Description:  Shifts the elements of a Q15 vector by a specified number of bits
 *
 * $Date:        18. March 2019
 * $Revision:    V1.6.0
 *
 * Target Processor: Cortex-M cores
 * -------------------------------------------------------------------- */
/*
 * Copyright (C) 2010-2019 ARM Limited or its affiliates. All rights reserved.
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Licensed under the Apache License, Version 2.0 (the License); you may
 * not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an AS IS BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "arm_math.h"

/**
  @ingroup groupMath
 */

/**
  @addtogroup BasicShift
  @{
 */

/**
  @brief         Shifts the elements of a Q15 vector a specified number of bits
  @param[in]     pSrc       points to the input vector
  @param[in]     shiftBits  number of bits to shift.  A positive value shifts left; a negative value shifts right.
  @param[out]    pDst       points to the output vector
  @param[in]     blockSize  number of samples in each vector
  @return        none

  @par           Scaling and Overflow Behavior
                   The function uses saturating arithmetic.
                   Results outside of the allowable Q15 range [0x8000 0x7FFF] are saturated.
 */

#if defined(ARM_MATH_MVEI)

#include "arm_helium_utils.h"

void arm_shift_q15(
	const q15_t *pSrc,
	int8_t shiftBits,
	q15_t *pDst,
	uint32_t blockSize)
{
	uint32_t  blkCnt;           /* loop counters */
	q15x8_t vecSrc;
	q15x8_t vecDst;

	/* Compute 8 outputs at a time */
	blkCnt = blockSize >> 3;
	while (blkCnt > 0U) {
		/*
		 * C = A (>> or <<) shiftBits
		 * Shift the input and then store the result in the destination buffer.
		 */
		vecSrc = vld1q(pSrc);
		vecDst = vqshlq_r(vecSrc, shiftBits);
		vst1q(pDst, vecDst);
		/*
		 * Decrement the blockSize loop counter
		 */
		blkCnt--;
		/*
		 * advance vector source and destination pointers
		 */
		pSrc += 8;
		pDst += 8;
	}
	/*
	 * tail
	 */
	blkCnt = blockSize & 7;
	if (blkCnt > 0U) {
		mve_pred16_t p0 = vctp16q(blkCnt);
		vecSrc = vld1q(pSrc);
		vecDst = vqshlq_r(vecSrc, shiftBits);
		vstrhq_p(pDst, vecDst, p0);
	}
}

#else
void arm_shift_q15(
	const q15_t *pSrc,
	int8_t shiftBits,
	q15_t *pDst,
	uint32_t blockSize)
{
	uint32_t blkCnt;                               /* Loop counter */
	uint8_t sign = (shiftBits & 0x80);             /* Sign of shiftBits */

#if defined (ARM_MATH_LOOPUNROLL)

#if defined (ARM_MATH_DSP)
	q15_t in1, in2;                                /* Temporary input variables */
#endif

	/* Loop unrolling: Compute 4 outputs at a time */
	blkCnt = blockSize >> 2U;

	/* If the shift value is positive then do right shift else left shift */
	if (sign == 0U) {
		while (blkCnt > 0U) {
			/* C = A << shiftBits */

#if defined (ARM_MATH_DSP)
			/* read 2 samples from source */
			in1 = *pSrc++;
			in2 = *pSrc++;

			/* Shift the inputs and then store the results in the destination buffer. */
#ifndef ARM_MATH_BIG_ENDIAN
			write_q15x2_ia(&pDst, __PKHBT(__SSAT((in1 << shiftBits), 16),
										  __SSAT((in2 << shiftBits), 16), 16));
#else
			write_q15x2_ia(&pDst, __PKHBT(__SSAT((in2 << shiftBits), 16),
										  __SSAT((in1 << shiftBits), 16), 16));
#endif /* #ifndef ARM_MATH_BIG_ENDIAN */

			/* read 2 samples from source */
			in1 = *pSrc++;
			in2 = *pSrc++;

#ifndef ARM_MATH_BIG_ENDIAN
			write_q15x2_ia(&pDst, __PKHBT(__SSAT((in1 << shiftBits), 16),
										  __SSAT((in2 << shiftBits), 16), 16));
#else
			write_q15x2_ia(&pDst, __PKHBT(__SSAT((in2 << shiftBits), 16),
										  __SSAT((in1 << shiftBits), 16), 16));
#endif /* #ifndef ARM_MATH_BIG_ENDIAN */

#else
			*pDst++ = __SSAT(((q31_t) * pSrc++ << shiftBits), 16);
			*pDst++ = __SSAT(((q31_t) * pSrc++ << shiftBits), 16);
			*pDst++ = __SSAT(((q31_t) * pSrc++ << shiftBits), 16);
			*pDst++ = __SSAT(((q31_t) * pSrc++ << shiftBits), 16);
#endif

			/* Decrement loop counter */
			blkCnt--;
		}
	} else {
		while (blkCnt > 0U) {
			/* C = A >> shiftBits */

#if defined (ARM_MATH_DSP)
			/* read 2 samples from source */
			in1 = *pSrc++;
			in2 = *pSrc++;

			/* Shift the inputs and then store the results in the destination buffer. */
#ifndef ARM_MATH_BIG_ENDIAN
			write_q15x2_ia(&pDst, __PKHBT((in1 >> -shiftBits),
										  (in2 >> -shiftBits), 16));
#else
			write_q15x2_ia(&pDst, __PKHBT((in2 >> -shiftBits),
										  (in1 >> -shiftBits), 16));
#endif /* #ifndef ARM_MATH_BIG_ENDIAN */

			/* read 2 samples from source */
			in1 = *pSrc++;
			in2 = *pSrc++;

#ifndef ARM_MATH_BIG_ENDIAN
			write_q15x2_ia(&pDst, __PKHBT((in1 >> -shiftBits),
										  (in2 >> -shiftBits), 16));
#else
			write_q15x2_ia(&pDst, __PKHBT((in2 >> -shiftBits),
										  (in1 >> -shiftBits), 16));
#endif /* #ifndef ARM_MATH_BIG_ENDIAN */

#else
			*pDst++ = (*pSrc++ >> -shiftBits);
			*pDst++ = (*pSrc++ >> -shiftBits);
			*pDst++ = (*pSrc++ >> -shiftBits);
			*pDst++ = (*pSrc++ >> -shiftBits);
#endif

			/* Decrement loop counter */
			blkCnt--;
		}
	}

	/* Loop unrolling: Compute remaining outputs */
	blkCnt = blockSize % 0x4U;

#else

	/* Initialize blkCnt with number of samples */
	blkCnt = blockSize;

#endif /* #if defined (ARM_MATH_LOOPUNROLL) */

	/* If the shift value is positive then do right shift else left shift */
	if (sign == 0U) {
		while (blkCnt > 0U) {
			/* C = A << shiftBits */

			/* Shift input and store result in destination buffer. */
			*pDst++ = __SSAT(((q31_t) * pSrc++ << shiftBits), 16);

			/* Decrement loop counter */
			blkCnt--;
		}
	} else {
		while (blkCnt > 0U) {
			/* C = A >> shiftBits */

			/* Shift input and store result in destination buffer. */
			*pDst++ = (*pSrc++ >> -shiftBits);

			/* Decrement loop counter */
			blkCnt--;
		}
	}

}
#endif /* defined(ARM_MATH_MVEI) */

/**
  @} end of BasicShift group
 */
